Support for an induction magnet blowout piece for circuit breakers



April 26, 1966 R. B. HEILMAN 3,248,506

SUPPORT FOR AN INDUCTION MAGNET BLOWOUT PIECE FOR CIRCUIT BREAKERS Filed Jan. 18, 1963 2 Sheets-Sheet 1 99 will INVENTOR. BY Ramona B. HEILMHN HIS QTTO'R'EEVJ SUPPORT FOR AN INDUCTION MAGNET BLOWOUT PIECE FOR CIRCUIT BREAKERS Filed Jan. 18, 1963 2 Sheets-Sheet 2 9g 9 9%) 27 & 3 97 96 ,5 [132 65 66b 1 mo, 60

IN VENTOR RAYMOND B Heumnw United States Patent 3,248,506 SUPPORT FOR AN INDUCTION MAGNET BLOW- OUT PIECE FOR CIRCUIT BREAKERS Raymond B. Heilman, Trenton, NJ., assignor to Heinemann Electric Company, 'Irenton, N..I., a corporation of New Jersey Filed Jan. 18, 1963, Ser. No. 252,485 Claims. (Cl. 200-147) hermetically sealed metal case which is insulated from' the current carrying portions of the circuit breaker and the circuit breaker is utilized in an ambient whose temperature may vary between extremely low and high values. One reason for this temperature variation is that, during certain conditions, the lead conductors to the circuit breakers may be at very high temperatures. At such times, while the overall temperature of the circuit breaker tends to increase, the temperature of the terminals particularly tends to increase, resulting in the tendency of the terminals to expand and contract, relative to the case, as the temperature of the terminals changes.

A feature of this invention is that an improved support for the induction magnet blowout piece is secured to the terminal so that a subassembly is formed that is, in contrast to some-prior art constructions, independent of the case. That is, in the present invention, the induction magnet blowout piece is .correctly supported relative to the stationary contact, independently of the case, thus facilitating attainment and maintainment of the correct relationship between the magnetic blowout piece and the stationary contact. w

The circuit breaker in which this invention is incorporated comprises two terminals, and the two terminals are constructed generally similar to each other except that one is connected by a conductor to the electromagnet of the circuit breaker and the other forms the stationary contact which cooperates with a movable contact, the latter being actuated by a linkage mechanism controlled by a handle (for manual operation) and by an electromagnet (for automatic tripping operation upon predetermined overloads).

Each of the two terminals comprises a central stud section of high strength and corrosion resistance secured to and surrounded along part of its length by a tubular sleeve of a material which is a high electrical conductive property, resulting in electrical shunting of the central stud. In one of the terminals, the tubular sleeve forms the stationary contact at one end, while in the other terminal, a conductor is connected between the electromagnet and the tubular sleeve.

In each terminal there is in insulator bushing connected to the metal case of the circuit breaker and encircling the tubular shunting sleeve and the central stud (for part of their lengths). The tubular sleeve and stud extend through the bushing and are movable relative to the bushing, upon thermal expansion and contraction, due to a flexible annular collar secured at its outer peripheral edge to the bushing and at its inner peripheral edge to the tubular sleeve.

The support for the induction magnet blowout piece comprises a metal arm secured to the blowout piece and a yoke portion frictionally clasping'a portion of the associated terminal. After the blowout support is secured Patented Apr. 26, 1966 ICC to the terminal, the blowout piece and at least the support arm portion extending above the stationary contact are embedded in an insulation, preventing an are from extending between the movable contact and the blowout piece.

The foregoing and other objects of the invention, the principles of the invention, and the best mode in which it is contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof. In the drawings,

FIG. 1 is a view in side elevation of a circuit breaker incorporating this invention showing the contacts open position;

FIG. 2 is an enlarged sectional view of the lower portion of the circuit breaker illustrated in FIG. 1, but the insulation shown in 'FIG. 1 surrounding the magnetic blowout and the upper part of the left terminal is omitted in FIG. 2;

FIG. 3 is a top view taken along the line 33 in FIG. 2, and

FIG. 4 is an exploded view of the left terminal in FIG. 2.

Referring to the drawings, a circuit breaker 10 is illustrated having a metallic case 11, preferably of stainless steel, and partly broken away in FIG. 1 to expose certain internal structure, through which extend terminals 12 and 13. The terminal 13 includes a stationary contact 15 at its upper end which cooperates with a movable contact 17 carried by a movable arm 18. The movable arm 18 is actuated by a linkage mechanism 29 controlled by an electromagnetic device 16, a counterweight suspension structure 19 being associated with the latter, all of which are described in detail and claimed in applications filed by Raymond B. Heilman and Harold H. Baker on December 24, 1962, Serial No. 246,699; by Raymond B. Heilman on January 18, 1963, Serial No. 252,404; and by Ronald Nicol on January 18, 1963, Serial No. 252,413; and consequently they are not described in detail herein. Manual opening andclosing of the contacts 15 and 17 is effectuated by a handle 21, whereas electromagnetic tripping of the contacts to the open position is controlled by the downward movement of the tube 26.

The linkage mechanism 20 comprises two groups of links referred to for convenience as the handle toggle or first group 23 and the main toggle or second group 24. Briefly, pivotal counterclockwise movement of the handle 21, starting from the open contacts position of FIG. 1, causes the handle toggle links 23 comprising the handle link 27 and a link of varying length 28 (joined together by a knee pintle 30) to move to the right and the handle force to be transmitted by a coupling link 32, from the link of varying length 28 to the knee pintle 33 of the main toggle links 24, the latter comprising the toggle links 36 and 37 and the catch link 39. The lower toggle link 37 is, in turn, connected to the movable contact arm 18, whereby movement of the handle 21 results in the movable arm 18 being rotated. in the counterclockwise direction, closing the contacts 15 and 17. In the closed .position of the contacts, the' catch link 39 is restrained 46 by the catch link 39) from the force of the opening springs 47.

When the tube 26 moves downwardly a sufiicient distance, upon predetermined overloads, the tube 26 pivots clockwise (FIG. 1) the suspension structure 19 sufficiently to engage the cradle lock and rotate the latter torelease the cradle 46 from its cradle lock, whereby the catch link 39 is released from its lock 45 and the upper end of the catch link 39 moves in the clockwise direction under the bias of the opening springs 47. This clockwise movement of the catch link 39 causes the main toggle (formed by links 36 and 37) to collapse due to the pressure of the opening springs 47, whereupon the contacts open. During the collapse of the main toggle links, the knee pintle 33 of the handle toggle is moved overcenter (toward the left) sutficientlyfor the spring 56 (carried by the link of varying length 28) to help reset the mechanism.

The bottom and initially separate part 60 of the stainless steel case 11 is provided with two circular holes 61 and 62 defined by two annular U-flanges 63 and 64, respectively, the free end rims 65 being inturned, into the case interior. Peripherally furnace brazed in a vacuum only to the inner annular surfaces 66 (and not brazed to the bases 66a of the U-shapes nor the outer annular surfaces 66b) are ceramic bushings 67 and 68, each of the latter extending through and into the case (in abutment with the bases 66a) and having a portion depending from the case, the bushings 67 and 68 being preferably formed from a high alumina ceramic.

Extending through axial holes 69 and 70, in each of the ceramic bushings 67 and 68, but annularly spaced from the cylindrical bushing walls defining the holes 69 and 70, so as to define annular spaces 57 and 58, are electrical conductors or shunt sleeves 71 and 72 secured to electrical conductors or studs 73 and 74, respectively, of high mechanical strength relative to the shunt sleeves but of lower electrical conductivity relative to the latter.

The sleeves 71 and 72 are secured to their respective bushings 67 or 68 by annular thin and flexible (relative to the other parts of the terminals) collars or washers 77 and 78, each of the latter being brazed at its outer circular peripheral portion to the associated bushing 67 or 68 (at the lower part thereof on the outside of the case 11) and brazed adjacent its inner circular peripheral portion to the outer surface of the associated sleeve 71 or 72.

As illustrated in FIG. 2, the collars 77 and 78 have a general U-shape in cross-section, and the shunt sleeves 71 and 72 each have an enlarged lower portion. The

collars 77 and 78 are placed around the shunt sleeves 71 and 72 with the inner surface of the collars 77 and 78 partly in abutment with the enlarged lower ends of the sleeves 71 and 72 and peripherally brazed to the outer surface of the shunt sleeves 71 and 72 just above their enlarged ends, a shoulder at the juncture of the enlarged ends with the remainder of the sleeves being used to receive rings 93 (FIG. 4) of the brazing material used during the brazing. The collars 77 and 78 are brazed at their peripheral outer portions to the lower enlarged portions of the bushings 67 and 68, brazing rings 94 being interposed between the two. The thickness of each collar is such that only a radial part of each of the spaces 69 and 70 is occupied by the peripheral portions that are brazed to the sleeves 71 and 72 and the collars do not extend very far into the spaces 69 and 70, as illustrated. Also, inclined spaces 57a and 58a are formed, in communication with the spaces 57 and 58, the spaces 57a and 58a being betweenthe portions of the collars which are brazed to the bushing 67 or 68 and the portions which are brazed to the sleeve 71 or 72. As illustrated, the enlarged lower portions of the bushings 67 and 68 are disposed below the flanges 63 and 64 and radially outward of the annular surfaces 66 of the flanges 63 and 64.

It is seen from the foregoing that axial and radial expansion and contraction of the studs 73 and 74 and of the sleeves 71 and 72 is accommodated by the axial and radial flexibility of the collars 77 and 78.

The shunt sleeves 71 and 72 are preferably formed from a silver-magnesium-nickel alloy and are mechan- 4. ically secured to the studs 73 and 74 by having three spaced, circumferential portions 82 thereof crimped (FIG. 4) into annular grooves 84 formed in the studs and circumferentially brazed thereto at the groove 84 also. The studs 73 and 74 are preferably formed from stainless steel and are threaded below the shunt sleeves 71 and 72, as illustrated, to receive external lead conductors (not illustrated) which are suitably biased by threaded connectors 79 and (FIG. 1) against annular depending beads 86 (at the lower end of the sleeves 71 and 72) to insure proper physical contact and electrical conduction, the beads 86 being below the lowest parts of the collars 77 and '78.

As illustrated in FIG. 1, an electrical conductor 90 is connected at one end to the sleeve 72 and to the coil of the electromagnet 16 at the other end. The coil is in turn connected to the movable arm 18 by a flexible conductor 91. The stationary contact 15 is integral with and formed by the upper closed end of the sleeve 71 so that when the contacts are in abutment, the electrical circuit is completed.

The circuit breaker, as illustrated, is provided with a U-shaped magnetizable member 96, preferably made of iron, having legs 97 connected by a bight 98 and further described and claimed in Raymond B. Hellman Patent No. However, unlike the arrangement disclosed in the mentioned patent, in this invention, the magnetizable member 96 is properly positioned by a support 99 comprising a yoke 101 and a finger 102 of electrically conductive material but nonmagnetic, such .as stainless steel, the yoke 101 frictionally and tightly clasping a circumferential part of the sleeve 71, as illustrated, and the finger 102 being brazed to the inside of the bight 98, between the legs 97.

Initially, the terminals 12 and 13 are assembled as separate similar units, since the terminal 13 is substantially the same as the terminal 12 prior to addition of the blowout member 96 and the embedding insulation material 106. The terminals 12 and 13 are then placed in proper position extending through the holes 61 and 62, with the enlarged ends of the bushings abutting the base of the U- shaped rims and the bushings are then brazed to the annular surfaces 66.

The magnetizable blowout member 96 is then added to the terminal 13 and the support 99 positioned so that the bottom surface of the magnetizable member 97 is above the surface of the contact 15. Thereafter, an electrical insulation material 106, FIG. 1, preferably a flowable silicone rubber compound, is painted on the magnetizable member 96 and the finger 99. Some of the insulation mater1al is also placed in the cavity formed by the curved surface 104 of the bushing 67 and the yoke 101 and overlies an annular shoulder formed by the end of the shunt sleeve 71 below the contact 15, as illustrated in FIG. 1.

The insulation 106 has elastic qualities permitting relative movement between the shunt sleeve 71 and the bush ing 67 without cracking the ceramic bushing or destroying the hermetic seal. The silicone rubber insulation 106 vulcanizes at room temperature and takes the shape illustrated in FIG. 1 although some does extend down into the annular space 57 between the sleeve 71 and bushing 67.

As partially illustrated in FIG. 1, silicone rubber insulation 106 is also applied to the upper end of the sleeve 72 (of terminal 12) to embed the connection between the conductor 90 and the sleeve 72, as well as filling the space 70.

From the foregoing it is seen that the insulation material 106 about the magnetizable member 96 and the support 99 therefor embed the last two mentioned elements but the insulation 106 has no effect on the magnetic lines of flux which are induced by the current in the magnetizable member 96 and the arc controlling function of the latter. However, if an arc should form, the insulation,

106 will prevent the arc from striking the magnetic blowout member 96.

Thus, as the terminal 13 expands and contracts long1- tudinally with temperature changes, the support 99 carries with the sleeve 71 the magnetizable member 96 at all times in proper relation with the surface of contact 15.

Further, as the unit is subjected to changes in temperature, the positions of the terminals 12 and 13 relative to the case part 60 change due to the flexibility in the flanges 63 and 65. More importantly, as the temperature changes, the sleeves and studs will expand and contract. Since the sleeves are spaced from the bushings by the annular spaces, and the collar is relatively thin and of U-shape, as illustrated, changes in the sleeves and studs are accommodated by the collars. The magnetic blowout member 96 remains in its correct position during such changes and is embedded in insulation so that any are that may tend to form on contact separation will be interrupted should it attempt to jump onto the blowout member.

After applying the rubber compound to the upper ends of the terminals 12 and 13 and allowing it to set sufficiently, assembly of the circuit breaker may be continued as follows. For this purpose, as illustrated in FIG. 2, there is secured to the left hand portion of the peripheral flange of the lower case part 60 an upstanding U-shaped (FIG. 3) assembly plate 110. Intermediate the legs of the assembly plate 110 are placed the two spaced and opposed frame plates 120, only one of which is shown in FIG. 1, between which is mounted the linkage mechanism 20, some of the linkage pintles extending through to engage the legs of the assembly plate 110, whereby the linkage mechanism is positioned relative to the lower case part 60.

Having described this invention, I claim:

1. In a circuit breaker comprising the combination of stationary and movable contacts, a mechanism for actuating the movable contact, an electromagnet for controlling the mechanism, an inductive magnetic blowout member positioned relative to said contacts to control the are that tends to form upon the separation of the contacts, a metallic case enclosing the contacts, mechanism and electromagnet, the improvement comprising a first terminal structure connected to said stationary contact, a second terminal structure connected to said electromagnet, said terminals extending through said case, each of said terminals comprising a ceramic bushing secured to said case, each bushing having an axial :hole, an electric current conductor secured to each bushing and extending through each hole therein from the outside of said case into the interior thereof and axially movable within the bushing, one of the conductors including a stationary contact, and a metallic, electrically conductive, support structure secured at one end to the current conductor which includes the stationary contact and secured to the magnetic blowout at the other end, whereby said magnetic blowout is maintained correctly positioned relative to said stationary contact as said stationary contact moves relative to said case.

2. The structure recited in claim 1 and further including electrical insulation material embeds said magnetic blowout member to electrically insulate it, whereby the .arc that tends to form upon contact separation is interrupted should it attempt to jump onto the blowout member due to the fact that the latter has the same electrical polarity as the stationary cont-act because of the electrically conductive support.

3. In a circuit breaker, the combination comprising stationary and movable contacts, a mechanism for actuating the movable contact, an electromagnet for controlling the mechanism, a metallic case enclosing the contacts, mechanism and electromagnet, a first terminal structure including said stationary contact, a second terminal structure connected to said electromagnet, said terminals extending through said case, the improvement comprising ible metallic ring secured peripherally to said bushing at one portion and secured peripherally at another diametrically spaced portion to said conductor.

4. In a circuit breaker including stationary and movable contacts, a case enclosing the contacts, a terminal structure connected to the stationary contact, said terminal structure which is connected to said stationary contact including a part which is movable relative to said case at approximately the same rate and in the same direcan induction magnetic blowout member secured to said tion as said stationary contact, an induction magnetic blowout member associated with the contacts to control the arcs that tend to form upon 'separation of the con tacts, the improvement comprising a metallic support electrically connected to the part of said terminal which is movable relative to said case and to said blowout memher for positioning the blowout member correctly with respect to the stationary contact, and electrical insulating material surrounding said blowout member so as to embed the latter the-rein, whereby the arc that tends to form upon contact separation interrupted should it attempt to jump onto the blowout member due to the fact that it has the same electrical polarity as the stationary contact because of its electrically conductive support.

5. In a circuit breaker having a pair of separable contacts opened on predetermined overloads by an electromagnetic device and a linkage, the improvement comprising a metal case formed by a plurality of parts, one of the case par-ts comprising a subassembly of two terminals spaced from each other and extending through the case part, one of said terminals forming in part a stationary contact, each terminal including an electrical conductor and an insulator and the latter electrically insulating the former from the case part, a flexible collar between each insulator and each electrical conductor to accommodate thermal expansion and contraction of the electrical conductor, a magnetizable member associated with the stationary contact for controlling the arcs that tend to form on contact separation, a metal support for the magnetizable member associated with the stationary contact for controlling the arcs that tend to form on contact separatron, said metal support being mechanically secured to the magnetizable member and to the electrical conductor of the terminal which includes the stationary contact for oint movement at all times, and an electrical plastic insulation embedding the magnetizable member and part of the support therefor.

References Cited by the Examiner UNITED STATES PATENTS 1,509,971 9/1924 Mershon 174--18 2,629,035 2/1953 Yingst 200-147 2,729,722 1/1956 Nelsen ZOO-J47 2,896,008 7/1959 Putz 174-50.56 2,995,639 8/1961 Panerai et al. ZOO-J68 3,038,054 6/1962 Naimer 200168 3,102,937 9/1963 Brunner 200147 3,141,082 7/1964 Hollyday 200-147 FOREIGN PATENTS 1,100,126 2/1961 Germany.

KATHLEEN H. CLAFFY, Primary Examiner.

ROBERT K. SCI-IAEFER, ROBERT S. MACON,

Examiners. P. E. CRAWFORD, Assistant Examiner. 

5. IN A CIRCUIT BREAKER HAVING A PAIR OF SEPARABLE CONTACTS OPENED ON PREDETERMINED OVERLOADS BY AN ELECTROMAGNETIC DEVICE AND A LINKAGE, THE IMPROVEMENT COMPRISING A METAL CASE FORMED BY A PLURALITY OF PARTS, ONE OF THE CASE PARTS COMPRISING A SUBASSEMBLY OF TWO TERMINALS SPACED FROM EACH OTHER AND EXTENDING THROUGH THE CASE PART, ONE OF SAID TERMINALS FORMING IN PART A STATIONARY CONTACT, EACH TERMINAL INCLUDING AN ELECTRICAL CONDUCTOR AND AN INSULATOR AND THE LATTER ELECTRICALLY INSULATING THE FORMER FROM THE CASE PART, A FLEXIBLE COLLAR BETWEEN EACH INSULATOR AND EACH ELECTRICAL CONDUCTOR TO ACCOMMODATE THERMAL EXPANSION AND CONTRACTION OF THE ELECTRICAL CONDUCTOR, A MAGNETIZABLE MEMBER ASSOCIATED WITH THE STATIONARY CONTACT FOR CONTROLLING THE ARCS THAT TEND TO FORM ON CONTACT SEPARATION, A MEATAL SUPPORT FOR THE MAG- 